cedures may 
ial film/filter 
lon, since the 
:dictable dif- 
n/filter com- 
:e into detec- 
South Pacific 
a prescribed 
zone, while 
fferent tech- 
tation. 
varies little 
iterpretation. 
ypes of pho- 
ot” principle 
t coasts and 
desirable by 
| conditions. 
n photo to 
ng roads or 
on oblique 
ited States, 
e millimeter 
ous photo- 
es a simple 
distance on 
> is known. 
quals 8 feet 
  
   
   
  
   
   
  
   
  
   
   
   
  
    
   
   
   
   
  
  
  
  
  
  
  
  
  
  
   
   
  
  
    
  
  
  
   
  
   
    
   
   
    
  
     
(691) 
on the ground. When an average of ten or twenty measurements must be 
rapidly made on each print of a coastal sortie, the value of a “direct reading” 
scale is obvious. 
The monocular folding or tubular magnifier found in American military 
photographic interpreter’s kits, is fitted with a transparent plastic diaphragm, 
inscribed with a portion of a 0.001-ft. scale and mounted in position under the 
lens so that small objects can be rapidly and accurately measured while being 
viewed under the magnifier. 
Certain additional equipment being contemplated or developed for pos- 
sible use in amphibious interpretation is still under security classification. Such 
developments consist mostly of special items designed as solutions to one par- 
ticular type of problem and not as replacements for the standard items. Im- 
proved models of nearly all the standard items are also under development. 
VI. Desired Improvements in Equipment or Techniques. 
Consideration of desirable improvements in equipment or techniques in- 
fringes necessarily on security classifications given certain projects now in pro- 
gress. Where security considerations are involved, neither current project nor 
the requirements for the future can be discussed in detail here. Some broad, 
general requirements may be noted, however: 
1. Better methods of depth determination from aerial photography. World 
War II methods are severely limited as to the conditions under which they 
may be used. Further, these methods have not proved themselves economically 
usable for peacetime underwater mapping. Methods which are economical, reli- 
able, and accurate under all conditions are urgently required. 
2. Accurate methods of predicting gradients and materials on the beach 
above the waterline. Comparatively slight variations in slope and composition 
of this unconsolidated medium may make considerable differences in the ability 
of vehicles to operate. 
3. A reliable system of trafficability prediction. This includes the develop- 
ment of suitable symbols or units in which trafficability can be expressed on 
maps of mosaics, the development of techniques for determining trafficability 
from the photo image, and the creation of suitable keys to enable the average 
military interpreter to render trafficability predictions. 
VII. Desirable Photographic Film, Filter, and Scale Combinations. 
Each photographic interpreter develops his own preferences for photo 
scale and quality. These are normally the result of his own area of experience, 
and may differ somewhat from the ideas of an equally well qualified analyst 
with a slightly different background. 
The whole field of optimum image size and quality for various fields of 
interpretation has been insufficiently investigated. Not only are the desirable 
scales and film/filter combinations unknown, but we have not yet determined 
just what in the way of basic image characteristics is required for the inter- 
preter to identify objects on photographs. Fundamental research being perform- 
ed by Dr. D. MacDonald of Boston University (6) and others may provide a 
foundation upon which conclusions in this field may be reached. 
The degree of detail available for interpretation is directly proportional to